Driving in Boston leaves much to be desired, and you don't have to be from Boston to know that Boston drivers are aggressive. It's a commonly accepted fact that drivers in Southie make sudden U-Turns in the middle of traffic. Also in Southie drivers double park a lot, so be prepared to leave a few minutes early to make sure your car is not blocked in.
Another common driving behavior in Boston is people driving in the "break down lane" (a lane designated for cars with flat tires) at the same pace as those driving in the normal lanes without slowing down for people to merge on or off the highway.
Be careful of the Commercial Street, Washington Street, Causeway Street, and Charlestown Bridge intersection. Endicott Street has a stop sign and not a stop light. Drivers do not know how to act at this stop sign and will often pull out in front of traffic at break-neck speeds.